Detection of Contact Voltage in Electric Distribution Systems

Transcription

1 Detection of Contact Voltage in Electric Distribution Systems David Kalokitis CTO Power Survey Company (888) PSC-2008

2 Who is Power Survey Company? Core business: Contact Voltage detection/mitigation services Technology R&D Formed in 2004 at Sarnoff Corporation Independent subsidiary of Sarnoff until 2007 Responsible for detection of more contact voltage hazards than any other group of organizations on earth combined US and Canadian utilities rely on Power Survey as an independent expert Headquartered in Kearny, NJ

3 What is Stray/Contact Voltage? In underground distribution areas, Stray Voltage, as it is often termed by the public, media and industry, is neither a new problem, nor specific to any utility or region. It is more correctly defined as Contact Voltage, an unintentional connection between a power distribution system and publicly accessible surfaces. Contact voltage is present in all distribution systems we have visited to date, and has been responsible for injury and death in many cities.

4 Contact Voltage Concerns Public Safety Hazard to general public (human and animal) Reliability Many contact voltage hazards are the manifestation of larger underground reliability problems including collapsed ducts, burned out services, system decay and degradation, construction damage etc

5 Where is Contact Voltage? Contact voltage is most commonly found in underground electric distribution areas Inner cities and Underground Residential Distribution Where buried infrastructure exists Densely populated areas increase potential for electrocution Heavy foot traffic Contact voltage is not just found in cold northern cities We have found significant problems in warmer, newer cities Children killed by contact voltage in Miami in recent years Indirect Contact with energized structures Standing water at energized structure extends hazard s reach

6 Common Root Causes Duct corrosion or collapse Neutral corrosion Light damage/removal Connections accessible to the public Improper wiring Chemical damage from salt Construction damage Grounding problems Failed insulation Damaged Conduit Poor workmanship Burned out neutral Failed conductors

7 Our Testing Power Survey has conducted contact voltage testing and uncovered major problems in these cities: Albany Atlanta Baltimore Boston Buffalo Chicago Columbus Cincinnati Detroit Indianapolis Jacksonville London Los Angeles Louisville Miami Milwaukee Minneapolis Multiple Cities Paris Pittsburgh Rochester San Diego Syracuse Toronto Washington Worcester NY GA MD MA NY IL OH OH MI IN FL UK CA KY FL WI MN NJ FR PA NY CA NY ON DC MA

8 Case Study: St. Catherine s Church Feb 28, V on fence Service duct cracked by tree roots under sidewalk Located using mobile detection and repaired

9 Contact Voltage Examples Part of Landscape Public Proximity Reliability Problems 33V found on Brooklyn mailbox caused by burned service leg underground. 108V found on streetlight on beach. Repaired corroded neutral. 60V found on Foster Av sidewalk & front lawn. Service replaced. Contact Voltage can exist on any surface above buried infrastructure

10 Common Energized Structures Street Lights Sidewalks Traffic Signals Pedestrian Crossings Manholes Fences Roadways Bus Shelters Access Hatches Phone Kiosk Voltage appearing on surfaces can change suddenly as fault conditions change

11 Locating Contact Voltage Goal: Find and eliminate energized surfaces and structures Method: Detection Any surface above buried infrastructure can be energized Testing assets alone is ineffective Best method is to sniff for leaks as is done in gas distribution systems Pinpoint energized structures or surfaces Troubleshoot Repair Detection is far more effective than inspection Asset lists limit scope of testing

12 Contact Voltage Survey Equipment Sophisticated truck mounted sensor system Hand-held instruments for localization GPS and mapping tools to track survey Trained Technicians Operate equipment Perform field investigations Track progress and record findings 12

13 Power Survey Company s SVD2000 Mobile Contact Voltage Detection System

14 SVD2000 Operation and Features Energized surfaces can be thought of as small radio transmitters The SVD2000 is a highly tuned receiver that works in close range to find hot spots Operates at speeds up to 20 MPH Range of over 30 ft. Sensitive down to 1 volt AC Enabling technology for detection process Subject to extensive independent lab testing per NYPSC requirements

15 Survey Elements Planning Select coverage areas Map generation Scale of operation Number of trucks Period of performance

16 Contact Voltage Technicians Trained in all aspects of contact voltage survey Rigorous training program Classroom elements Hands on demonstrations On the Job training Performance audits

17 Field Investigation Measure voltage Gather data Cone and tape area Deploy Standby Personnel Prepare report for repair activity Survey Tracking GPS System Route planning Progress tracking

18 Regulatory Considerations All utility initiated testing program have been reactive Following injury or death Regulation is necessary to drive proactive testing Find problems before public incident Ensure public safety Require utilities to perform repeated testing Contact Voltage regulation already exists in some states New York serves as an excellent model

19 Summary of Concerns Contact voltage exists in all distribution systems CV is the product of a fault or failure Protection devices largely non-existent Voltage can change suddenly Where detection is performed, density of CV findings is high Electric Distribution systems should be swept for leaks much like gas and other distribution systems Regulation is crucial to ensuring public safety